A radio access network such as Long Term Evolution (LTE) standardized by 3rd Generation Partnership Project (3GPP) defines access restriction in which, when a particular radio base station is congested due to a temporary increase in communication traffic or the like, a radio communication terminal (a mobile station) restricts initiation of communication based on broadcast information transmitted from the radio base station.
The following is also defined: in a case where a radio base station or a network apparatus (such as a switch) cannot accept a call request from a radio communication terminal due to congestion, the network apparatus responds to the radio communication terminal with a Service reject to reject the call request.
Further, in recent years, so-called Device-to-Device (D2D) communication is being discussed by 3GPP. In D2D communication, a radio communication terminal performs direct communication with another communication terminal without involving a radio base station (for example, Non-patent Document 1). Such D2D communication not involving a radio base station or a network apparatus can enhance the possibility that a radio communication terminal can originate a call even during congestion like the one described above.